1. Field of the Invention
The present invention relates to a lockbolt and, more particularly, to a lockbolt that displaces unwanted material during its installation.
2. Background Information
Lockbolts are commonly used where high-strength fasteners are required, such as aircraft fuel tanks and aircraft cabins. Typically, a lockbolt collar is provided for use with a lockbolt 100, shown in FIG. 1. The collar is slid over that portion of the lockbolt which extends through overlapped plate-like members. When the collar is properly swaged to mate with the lockbolt, the resulting lockbolt joint provides a reliable, high-strength fastener for the members.
Recently, viscous material, such as a sealant, has been applied to fay-surfaces of the plate-like members to reduce the potential of any corrosion forming between the plate-like members. The sealant is typically applied at a thickness of 0.003 to 0.005 inches. When such a significant amount of sealant is used, it causes a ring of the sealant to form inside any prepared holes within the plate-like members (i.e. lap splices), especially when the members are squeezed together. When the lockbolt 100 is passed through one of the prepared holes, swaging threads 102 on the lockbolt 100, which are designed to engage the lockbolt collar, often become contaminated with the sealant. Once contaminated, the swaging threads 102 must be properly cleaned by a mechanic prior to mating the lockbolt collar to the lockbolt 100. This process is tedious and time-consuming, increasing the workload on all the mechanics that are installing the lockbolts 100. If the swaging threads 102 of the lockbolts 100 are not properly cleaned prior to swaging the collar onto the lockbolt 100, then the resulting joint is considered defective and the collar is removed by force and the lockbolt 100 and the collar replaced.
Accordingly, for the foregoing reasons, there is a need in the fastening art for an apparatus and method that eliminates the need to clean the swaging threads of a lockbolt prior to swaging a collar onto the lockbolt after the lockbolt has been inserted into a contaminated area.